Electromechanical lock devices that include an electrically co-acting or controlled release mechanism for manoeuvring a lock cylinder are known to the art. Such lock devices are described in for example U.S. Pat. No. 5,839,307 and the Swedish patent SE 9904771-4. It is there described how an actuator is rotated by means of an electric motor. The actuator in turn permits or prevents the movement of a side bar. A way to manipulate such a latch mechanism is to try to hammer on the lock or in another way try to rotate the actuator to the release position.
The European patent publication EP 1 134 335 A2 describes a lock device, wherein a spring is used for mechanically returning an actuator to a latching position. This design is shown in FIG. 1, wherein it is evident that a returning pin presses on a leg of the spring, which in turn presses on a toothed surface of an actuator. The spring disclosed in this document is fixated by means of a cover and has returning of the actuator to latching position as only function. It is also comparatively complex to assemble.